Matrix drier and shrinker



Dec. 27, 1949 QC, BAKER 2,492,348

MATRIX DRIER AND SHRINKER 5 Sheets-Sheet 1 Filed April l5, 1946 BY lDec. 27, 1949 c. c. BAKER MATRIX DRIER AND SHRINKER Filed April l5, 19463 Sheets-Sheet 2 INVENTOR. CRAIG C BAKER Illll HHH Illllm l v AT TORNEYDec. 27, 1949 C, C, BAKER 2,492,348

MATRIX DRIER AND SHRINKER Filed April 15, 1946 3 Sheets-Sheet 3 27 23 2523 2| 22 L/ l'lll l I7 2 1 2o la 6 s l INVENTOR CRAG C BAKER ATTORNEYPatented Dec. 27, 1949 UNITED STATES PATENT OFFICE MATRIX DRIER ANDSHRINKER Craig C. Baker, Los Angeles, Calif.

Application April 15, 1946, Serial No. 662,241

4 Claims.

This invention relates to the drying of moist matrices in preparationlfor their use as molds for the casting of stereotype plates for rotaryprinting presses, especially newspaper presses.

More particularly this invention relates to that class of@ machinescommonly known as vacuum formers'or driers in which the matrix or mat isheld by vacuum against a curved iirm surface and subjected to dryingheat.

It is desirable to obtain the maximum amount of shrinkage in the matrixduring the drying and forming of the same, for the shrinking o thematrix, or condensing of the mat, reduces the size of the final printedpage and consequently enables a saving in paper to be made.

The principal object of the present invention is to provide an improveddevice to perform the preliminary drying and forming of the matrix whichwill promote greater shrinkage of the matrix.

In the course of my experiments to obtain greater shrinkage in thematrix I found that both the high vacuum, (that is where the degree ofrarifaction is great) and high degree of heat employed in the presentvacuum formers and driers have a tendency to retard the shrinkage in thematrix or mat. I found also that most of the shrinkage will take placeduring the earlier stages of the drying.

Another object of this invention therefore is to provide a matrix drierand preliminary former in which a lower vacuum. (that is where thedegree of rarifaction is not great) is required for holding the matrixfirmly against the forming plate during the initial stages of thedrying.

A further object of this invention is to provide an improved heatingmedium whereby the matrix, at least during the early stages of thedrying, will not be required to be subjected to the intense heat nowemployed in matrix driers and formers.

An additional object is to provide an improved drier and shrinker inwhich adjustable spring pressure applied against the two straight edgesof the matrix during the drying will aid in increasing the matrixshrinkage.

A further object of this invention is to provide a device for drying,forming, and shrinking the matrix in which the actual amount ofshrinkage which takes place in the width of the matrix will beconstantly indicated.

A still further object is to provide a drier and shrinker with a controlgoverned by a predetermined desired amount of shrinkage of the matrix,whereby the operation of the device will be 2 automatically halted whensuch predetermined amount of shrinkage has occurred.

The manner in which these objects and incidental advantages are attainedwith my invention will be explained in connection with the followingbrief description of my improved matrix drier and shrinker. In thefollowing description reference is to be made to the accompanyingdrawings, in which:

Fig. 1 is a side elevation of my improved drier and shrinker withportions of the outside casing broken away to show the generalarrangement of the interior members and parts;

Fig. 2 is a vertical section taken on line 2-2 of Fig. 1, drawn to aslightly smaller scale and with parts shown broken away for the sake ofclarity;

Fig. 3 is a sectional plan view corresponding to line 3-3 of Fig. 1,drawn to a still smaller scale, and illustrating the foot treadle ormeans for releasing the matrix in the device;

Fig. 4 is a view in perspective of the entire device;

Fig. 5 is a fragmentary view of the shrinkage indicator;

Fig. 6 is a plan view, partly in section, taken on the line 6 6 of Fig.1, showing the matrix in place in my device;

Fig. 7 is an enlarged fragmentary sectional view taken on line 1-1 ofFig. 6, illustrating the operation and function of the side holdingbars; and

Fig. 8 is an enlarged fragmentary section taken on line 8-8 of Fig. 6showing further details in connection with the side holding bars.

My matrix drier and shrinker is not intended to serve as a completesubstitute for the customary vacuum former and drier, but, morecorrectly, should be described as a pre-drier and shrinker, performingpartial drying and increased shrinking of the matrix preliminary to thefinal drying and forming of the matrix.

The nal stage in the drying and forming is intended to be accomplishedby the present customary former and drier in which the matrix may besubjected to higher temperature and higher vacuum to speed up the finalstage of the drying and forming.

Referring rst to Figs. 1 and 2, a vacuum chamber I, having a curved,perforated top wall 2 for supporting the matrix, is mounted on suitablesupporting brackets within the cabinet or housing 3. A blower, orair-exhausting means, l is mounted` below the vacuum chamber l, and isconnected therewith by manifolds or ducts 5 and 6. A suitabledischarging outlet 'I is provided for the air-exhausting means enablingthe air and moisture exhausted from the vacuum chamber to escape throughan opening I2 in the lower portion of the housing. The air-exhaustingmeans d is provided with the usual exhaust fan (not shown) driven by amotor 8 through suitable belt and pulley connections.

A pair of side holding bars 23 extend in parallel horizontal position onthe top of the vacuum chamber, along each side respectively, andparallel to the axis of curvature of the perforated top 2 of the vacuumchamber. One of the purposes of these bars is to engage and hold theopposite straight sides of the matrix. These bars are movably mounted soas to slide laterally towards or away from each other in unison whileresting on the top of the vacuum chamber.

Brackets I6, extend downwardly from the vacuum chamber I, being locatedadjacent the four corners of the vacuum chamber respectively. Ahorizontal stub shaft I5 is secured in each bracket I6 and a rocker armI3 is pivotally mounted on each stub shaft I5. The rocker arms I3 aretubular and a plunger I`I, (see Figs. 2 and 8), is slidably mounted inthe top portion of each rocker arm I3. A spring I8 on each plunger I'I,having one end bearing against the enlarged bottom end I9 of the plungerand the other end against a retaining sleeve screwed in the top of thearm I 3, tends to pull the plunger downwardly. The top ends of theplungers I I are pivotally connected to wrist pins 22 mounted in theends of the side holding bars 23. Thus the plungers I'I keep the sideholding bars 23 bearing on the top perforated surface of the vacuumchamber.

In Fig. 7 it will be noted that the longitudinal edge of the holdingbars 23 adjacent the matrix 2'I is formed with a beveled notch oroverhanging ridge 25 ,to extend over the matrix edge and keep the matrixedge pressed down against the perforated top 2 of the vacuum chamber.

To the bottom end of each rocker arm I3 a link 28 is pivotallyconnected, these links being shown most clearly in Fig. 2. The innerends of each pair of these links 28 are pivotally mounted at 3I to theupper end of a vertical rod 30. Each of the two vertical rods 30 (seealso Fig. 1) slides through a bracket 33 secured to the side wall of thehousing or cabinet. A spring 32 is mounted on each rod 30 and is heldunder adjustable compression between the bracket 33 and adjusting nut 34carried on the rod 30. The bottom ends of the two rods 38 are joined bya horizontal bar (Fig. 1) and a suitable foot lever or treadle 29 ismounted in the bottom of the cabinet and bears on the bar 35 so thatdownward pressure on the free end of the treadle 29 will operate to pullthe two vertical rods 30 downwardly vagainst the force of their springs32. The foot treadle is accessible to the operator through the openingI2 at the bottom of the cabinet as shown in Fig. 4.

As apparent from Fig. 2, downward pressure on the foot treadle 29,pulling the rods 30 downwardly, will cause the links 28 to pull thebottom ends of the rocker arms I3 inwardly. This will result in theupper ends of the rocker arms I3 and plungers I1 being moved outwardlywith the result that the holding bars 23 will be moved outwardly or awayfrom each other.

When a matrix is to be inserted in the device the foot treadle ispressed down causing the bars 23 to be moved outwardly and held in suchposition while the matrix is being placed on the perforated top 2 of thevacuum chamber I. Then the treadle is gradually released and the bars23, due to the action of the springs 32, move towards each other untilthey engage the respective edges of the matrix. The `holding bars 23 notonly insure the proper positioning of the matrix on the perforatedsurface but also at all times keep the straight edges of the matrix heldrmly in contact with the surface on which the matrix is supported. Therest of the matrix is held firmly against this top surface of the vacuumchamber by the\`suction through the perforations in the top into\thevacuum chamber I due to the operation ofthe air exhausting means 4.

However, in my invention these holding bars 23 perform an importantfurther function. The normal action of the springs 32, tending to pushthe rods 30 upwardly and the holding bars 23 inwardly towards eachother, causes these bars 23 to exert lateral pressure along bothlongitudinal side edges of the matrix and this lateral pressure orcompression of the matrix, particularly during the first stages 'of thedrying of the matrix, increases the shrinkage of the matrix. This is anovel and important feature of my invention. The amount of lateralpressure exerted on the matrix by the holding bars 23 can be varied byadjusting the tension of the springs 32 through the medium of theadjusting nuts 34. The lateral compression must of course not be toostrong or else there might be a tendency for the matrix to buckle, andthe amount of lateral compression which may safely be exerted willdepend to some extent upon the height of the vacuum maintained in thevacuum chamber, since the greater the vacuum the more firmly will thematrix be held by suction against the perforated top of the vacuumchamber. On the other hand, since the holding bars 23 will hold thelongitudinal side edges of the matrix firmly against this top surface atall times, a lower vacuum can be maintained in the vacuum chamber thanis ordinarily required in ordinary vacuum formers and driers, and noexcessive passage of air under the sides of the matrix into the vacuumchamber, which would decrease the vacuum, will occur. As mentionedpreviously, I have found that the maintenance of a low vacuum, insteadof a high vacuum, also increases the shrinkage of the matrix and thuswith my device I preferably maintain a low vacuum and adjust the springs32 accordingly.

Below one end of the vacuum chamber I I provide a control or shut-oilswitch 3'I (Figs. 1 and 2). This switch 3'I is connected with the motor8, which operates the blower 4, and is also connected with the heatingelement to be described later, so that the operation of the shut-offswitch 31 win result i shutting off the current both to the motor and tothe heating element. The switch 31 includes a spring-controlled plunger40 which extends downwardly. A bracket arm 38 (Fig. l) is adjustablymounted, by means of a suitable screw clamp 39, near the top of thevertical rod 30 below the switch 31 and is so arranged as to contact theplunger 40 of the switch 3`I and push the plunger upwardly, thusoperating the shut-off switch 31, when the rod 30 rises a predeterminedamount. But the upward movement of the rods SI1-will, as apparent fromFig. 2, depend upon the lateral shrinkage of the matrix which willpermit the holding bars 23 to move inwardly, the bottom ends of therocker arms I3 to swing outwardly, and the inner ends of the links 28 tobe pushed upwardly. In other words, the shut-off switch 3'I, by properadjustment of the bracket arm 38, can be caused to operate automaticallywhenever a desired predetermined shrinkage has occurred in the matrix.This is another important feature of my invention.

In order to determine the amount of shrinkage which has occurred at anytime in the matrix during the operation of my device I provide anindicating or calipering means connected with one of the holding bars 23or rocker'arms I3.

In Figs. 1 and 5 I show a simple form of such indicating meanscomprising a pointer 44 secured to one of the rocker arms I3. Thispointer has an off-set end which extends through a curved slot 45 in theside of the cabinet or housing 3. A suitable indicating scale 46 ismarked above the slot 45 to indicate te exact position of the rockerarm, and, since all the rocker arms operate simultaneously and to thesame extent, an indicator attached to one of the rocker arms I3 willsuffice for determining correctly the shrinkage of the matrix. Othercalipering means, associated with the holding bars 23, rocker arms I3,or rods 3U, could of course be substituted for ,he simplified meanswhich I have shown.

In place of the electrical heating and drying elements customarilyemployed in matrix farmers and driers I employ a plurality of infra-redlamps 3B (Fig. 2) for this purpose. Since one of the objects of myinvention is to avoid the use of the intense heat customarily employedin the drying of the matrix, particularly during the first stages of thedrying and shrinking of the matrix, I have found that infra-red lampsare highly satisfactory in providing just the right amount of dryingheat during the preliminary drying and shrinking of the matrix for themost eilicient accomplishment of my purpose.

These infra-red lamps are mounted in sockets supported in a curved plate41 forming the bottom of a closed housing 48 which contains suitableelectrical wiring connections and which is removably and adjustablysupported in an opening 49 (see also Fig. 4) provided in the top of thecabinet 3. The cabinet 3 is formed with a downwardly extending flange 50about the opening 49, and rows of adjustitng holes 5I in the flange 50,in vertical alinement with registering holes in the sides of the housing48 for the insertion of supporting screws, enable the housing 48, andwith it the infra-red lamps 36, to be set closer to, or further awayfrom, the matrix, or enable the housing 4-8 and lamps to be entirelyremoved from the top of the cabinet 3 when any repairs or replacementsare required in the heating element. The bottom plate 41, in which thelamps 36 are supported, has a curvature of substantially the same radiusas the top of the vacuum chamber I, so that all portions of the matrixwill be approximately the same distance from the lamps.

The front wall of the cabinet 3 is provided with a suitable hinged door24, located above the vacuum chamber' I, extending practically theentire width of the cabinet, to enable the matrix to be easily placedwithin or removed from the device.

As previously mentioned, my drier and shrinker is not designed to takethe place entirely of the matrix formers and drlers now at present inuse, but `is intended primarily to be employed only i of the matrix,thus during the period of vgreatest shrinkage. After the predeterminedor desired amount of shrinkage has been obtained in my device it isintended that the matrix then be removed. The vacuum suction is shut 01Tand the foot treadle 29 is pressed down to enable the matrix to belifted from the perforated top 2 of the vacuum chamber. Then the matrixis placed in an ordinary vacuum dryer and former, such, for example, asthat described in U. S. Letters Patent No. 1,960,697, of Cochran, etal., dated May 29, 1934, in which the matrix can be subjected to ahigher degree of heat and higher vacuum. This higher heat and vacuumwill speed up the nal drying of the matrix. Inasmuch as the desiredshrinkage will have occurred in the matrix before its removal from mydevice, the fact that very little shrinkage will occur under the hightemperature and high vacuum during this last and final drying andforming stage will not then matter.

I claim:

l. In a device of the character described, a vacuum chamber, aperforated wall on said vacuum chamber, air-exhausting means connectedwith said chamber, a pair of matrix-holding pressure bars positioned onsaid wall and adapted to engage the longitudinal side edges of thematrix, pressure means causing said bars normally to move towards eachother to press the longitudinal side edges of the interposed matrixinwardly and thereby cooperate with and increase the tendency of thematrix to shrink laterally while drying, bar-disengaging means formoving said bars outwardly away from the matrix edges, heating means forsupplying heat to the exposed surface of the matrix when said matrix ispositioned on said wall, a control connected with said heating means andsaid air-exhausting means adapted, when actuated, to stop the operationof said heating means and said air-exhausting means, an actuatingelement for said control, said actuating element connected with saidbarpressure means and adapted to actuate said control and thereby stopthe operation of said heating means and said air-exhausting means whenthe shrinkage of the matrix has caused said holding bars to moveinwardly a predetermined distance.

2. In a stereotype matrix former and drier, a vacuum chamber, aperforated wall on said vacnum chamber, air-exhausting means connectedwith said chamber, a pair of matrix-holding pressure bars substantiallyparallel to each other positioned on said wall and adapted to engage thelongitudinal side edges of the matrix, adjustable spring pressure meanscausing said bars normally to move towards each other to press thelongitudinal side edges of the interposed matrix inwardly and thereby'cooperate with and increase the tendency of the matrix to shrinklateraliy while drying, bar-disengaging means for moving said barsoutwardly away from the matrix edges, heating means for supplying heatto the exposed surface of the matrix when said matrix is positioned onsaid wall, a control connected with said heating means adapted, whenactuated, to stop the operation of said heating means, an adjustableactuating element for said control, said actuating element connectedwith said bar-pressure means and adapted to actuate said control andthereby stop the operation of said heating means when the shrinkage ofthe matrix has caused said holding bars to move inwardly a predetermineddistance.

3. In a stereotype matrix former and drier, a

vacuum chamber, a perforated wall on said vacuum chamber, air-exhaustingmeans connected with said chamber, a pair of matrix-holding pressurebars substantially parallel to each other positioned on said wall andadapted to engage the longitudinal side edges of the matrix, adjustablepressure means causing said bars normally to move towards each other topress the longitudinal side edges of the interposed matrix inwardly andthereby cooperate with and increase the tendency of the matrix to shrinklaterally while drying, bar-disengaging means for moving said barsoutwardly away from the matrix edges, heating means for supplying heatto the exposed surface of the matrix when said matrix is positioned onsaid wall, a control connected with said heating means and saidairexhausting means adapted, when actuated, to stop the operation ofsaid heating means and said air-exhausting means, an actuating elementfor said control, said actuating element connected with saidbar-pressure means and adapted to actuate said control and thereby stopthe operation of said heating means and said air-exhausting means whenthe shrinkage of the matrix has caused said holding bars to moveinwardly a predetermined distance.

4. A device of the character described including a vacuum chamber, aperforated wall on said vacuum chamber, airexhausting means connectedwith said chamber, a pair of matrix-holding pressure bars substantiallyparallel to each other positioned on said wall and adapted to engage thelongitudinal side edges of the matrix, ad-

justable spring pressure means causing said bars normally to movetowards each other to press the longitudinal side edges of theinterposed ma.-

trix inwardly and thereby cooperate with and increase the tendency ofthe matrix to shrink laterally while drying, bar-disengaging means formoving said bars outwardly away from the matrix edges, heating means forsupplying heat to the exposed surface of the matrix when said matrix ispositioned on said wall, and a control connected with said heating meansand said air-exhausting means adapted, when actuated, to stop theoperation of said heating means and said air-exhausting means, anadjustable actuating element :for said control, said actuating elementconnected with said bar-pressure means and adapted to actuate saidcontrol and thereby stop the operation of said heating means and saidair-exhausting means when the shrinkage of the matrix has caused saidholding bars to move inwardly a predetermined distance.

CRAIG C. BAKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

